P0172 and P0175,,ideas?


New Member
I just checked my codes from the most recent check engine light. Running rich bank 1 and 2..I have done the following..replaced Air filter (previous was seriosly dirty) cleaned out the MAF with MAF cleaner (or at least i think i have, i sprayed that stuff all in the throttle body)..any other ideas..maybe a purge valve? (if so, has anyone replaced one??)


Profile Violation
To clean the MAF you need to remove the portion WITH the MAF
in it, and spray clean it with MAF Cleaner. The MAF is not in the
throttle body, it's in the air-box, in the plastic tube that directly
exits the airbox.

Too much fuel can also be leaking injectors. That basically means, when
it is closed, it still leaks fuel into the engine, thus it really never closes.

  • A clogged, stuck, or leaking fuel injector
  • Faulty fuel regulator
  • Dirty or faulty mass air flow sensor
  • Faulty coolant temperature sensor
  • Faulty thermostat
  • ECM needs reprogramming
  • Dirty or faulty oxygen sensor
  • Vacuum leak
  • Fuel delivery problem
  • Incorrect fuel pressure
How does a mechanic diagnose the P0175 code?
  • Checks the fuel pressure
  • Inspects the fuel injectors for restrictions
  • Checks fuel injector pulse
  • Examines the fuel lines for pinches or cracks
  • Inspects all vacuum lines for cracks and deterioration
  • Inspects the oxygen sensors
  • Uses a scan tool to read the engine temperature, then compares the findings to an infrared thermometer
Common mistakes when diagnosing the P0175 code?
  • Not checking the temperature of the engine with a scan tool and comparing it to a thermometer
  • Deeming a component bad without verifying through testing
How serious is the P0175 code?
  • A system that is running too rich will force the catalytic convertor to filter out more pollutants, which will shorten the lifespan of the catalytic convertor
  • The resulting increased gas consumption could be very expensive
  • Improper air fuel ratio causes the engine to work harder, which will shorten the lifespan of the engine
  • The engine will create increased levels of harmful pollutants
What repairs can fix the P0175 code?
  • Replacing cracked or broken vacuum lines
  • Cleaning or replacing oxygen sensors
  • Cleaning or replacing mass air flow sensor
  • Reprogramming of the ECM
  • Replacing the fuel pump
  • Replacing the fuel filter
  • Replacing a damaged or pinched fuel line
  • Replacing a faulty fuel injector
  • Replacing a stuck thermostat
  • Replacing a faulty coolant temperature sensor
Additional comments for consideration regarding the P0175 code
It is strongly suggested that you verifyin that the cooling system of the vehicle is working correctly. If the vehicle is running abnormally cool, the engine will always run in a rich condition. This is because the ECM is designed to run at a rich rate when cold to help warm the engine up faster. If the coolant temperature sensor is faulty or the thermostat is stuck open, the vehicle may never reach a warm temperature, which will cause it to always run in a rich condition.